text: #include "emu.h"
  
  
  UINT8 *wc90b_fgvideoram,*wc90b_bgvideoram,*wc90b_txvideoram;
  
  UINT8 *wc90b_scroll1x;
  UINT8 *wc90b_scroll2x;
  
  UINT8 *wc90b_scroll1y;
  UINT8 *wc90b_scroll2y;
  
  UINT8 *wc90b_scroll_x_lo;
  
  static tilemap_t *tx_tilemap,*fg_tilemap,*bg_tilemap;
  
  
  
  
  /***************************************************************************
  
    Callbacks for the TileMap code
  
  ***************************************************************************/
  
  static TILE_GET_INFO( get_bg_tile_info )
  {
  	int attr = wc90b_bgvideoram[tile_index];
  	int tile = wc90b_bgvideoram[tile_index + 0x800];
  	SET_TILE_INFO(
  			9 + ((attr & 3) + ((attr >> 1) & 4)),
  			tile,
  			attr >> 4,
  			0);
  }
  
  static TILE_GET_INFO( get_fg_tile_info )
  {
  	int attr = wc90b_fgvideoram[tile_index];
  	int tile = wc90b_fgvideoram[tile_index + 0x800];
  	SET_TILE_INFO(
  			1 + ((attr & 3) + ((attr >> 1) & 4)),
  			tile,
  			attr >> 4,
  			0);
  }
  
  static TILE_GET_INFO( get_tx_tile_info )
  {
  	SET_TILE_INFO(
  			0,
  			wc90b_txvideoram[tile_index + 0x800] + ((wc90b_txvideoram[tile_index] & 0x07) << 8),
  			wc90b_txvideoram[tile_index] >> 4,
  			0);
  }
  
  
  
  /***************************************************************************
  
    Start the video hardware emulation.
  
  ***************************************************************************/
  
  VIDEO_START( wc90b )
  {
  	bg_tilemap = tilemap_create(machine, get_bg_tile_info,tilemap_scan_rows,     16,16,64,32);
  	fg_tilemap = tilemap_create(machine, get_fg_tile_info,tilemap_scan_rows,16,16,64,32);
  	tx_tilemap = tilemap_create(machine, get_tx_tile_info,tilemap_scan_rows, 8, 8,64,32);
  
  	tilemap_set_transparent_pen(fg_tilemap,15);
  	tilemap_set_transparent_pen(tx_tilemap,15);
  }
  
  
  
  /***************************************************************************
  
    Memory handlers
  
  ***************************************************************************/
  
  WRITE8_HANDLER( wc90b_bgvideoram_w )
  {
  	wc90b_bgvideoram[offset] = data;
  	tilemap_mark_tile_dirty(bg_tilemap,offset & 0x7ff);
  }
  
  WRITE8_HANDLER( wc90b_fgvideoram_w )
  {
  	wc90b_fgvideoram[offset] = data;
  	tilemap_mark_tile_dirty(fg_tilemap,offset & 0x7ff);
  }
  
  WRITE8_HANDLER( wc90b_txvideoram_w )
  {
  	wc90b_txvideoram[offset] = data;
  	tilemap_mark_tile_dirty(tx_tilemap,offset & 0x7ff);
  }
  
  
  
  /***************************************************************************
  
    Display refresh
  
  ***************************************************************************/
  
  static void draw_sprites(running_machine *machine, bitmap_t *bitmap, const rectangle *cliprect, int priority )
  {
  	UINT8 *spriteram = machine->generic.spriteram.u8;
  	int offs, sx, sy;
  
  	/* draw all visible sprites of specified priority */
  	for ( offs = machine->generic.spriteram_size - 8 ; offs >= 0 ; offs -= 8 )
  	{
  		if ( ( ~( spriteram[offs+3] >> 7 ) & 1 ) == priority )
  		{
  			int code = ( spriteram[offs + 3] & 0x3f ) << 4;
  			int bank = spriteram[offs + 0];
  			int flags = spriteram[offs + 4];
  
  			code += ( bank & 0xf0 ) >> 4;
  			code <<= 2;
  			code += ( bank & 0x0f ) >> 2;
  
  			sx = spriteram[offs + 2];
  			if (!(spriteram[offs + 3] & 0x40)) sx -= 0x0100;
  
  			sy = 240 - spriteram[offs + 1];
  
  			drawgfx_transpen( bitmap, cliprect,machine->gfx[17], code,
  					flags >> 4, /* color */
  					bank & 1,   /* flipx */
  					bank & 2,   /* flipy */
  					sx,
  					sy,15 );
  		}
  	}
  }
  
  VIDEO_UPDATE( wc90b )
  {
  	tilemap_set_scrollx(bg_tilemap,0,8 * (wc90b_scroll2x[0] & 0x7f) + 256 - 4 + (wc90b_scroll_x_lo[0] & 0x07));
  	tilemap_set_scrolly(bg_tilemap,0,wc90b_scroll2y[0] + 1 + ((wc90b_scroll2x[0] & 0x80) ? 256 : 0));
  	tilemap_set_scrollx(fg_tilemap,0,8 * (wc90b_scroll1x[0] & 0x7f) + 256 - 6 + ((wc90b_scroll_x_lo[0] & 0x38) >> 3));
  	tilemap_set_scrolly(fg_tilemap,0,wc90b_scroll1y[0] + 1 + ((wc90b_scroll1x[0] & 0x80) ? 256 : 0));
  
  	tilemap_draw(bitmap,cliprect,bg_tilemap,0,0);
  	tilemap_draw(bitmap,cliprect,fg_tilemap,0,0);
  	draw_sprites(screen->machine, bitmap,cliprect, 1 );
  	tilemap_draw(bitmap,cliprect,tx_tilemap,0,0);
  	draw_sprites(screen->machine, bitmap,cliprect, 0 );
  	return 0;
  }
  